Trig help! cos(x)=1/2?

cos(x) = 1/2
As cos(x) is positive in the first quadrant and the fourth quadrant, the first positive solution for x is π/3 and the first negative solution is -π/3.

The first three positive solutions :
x = π/3
x = (-π/3) + 2π = 5π/3
x = π/3 + 2π = 7π/3

The first three negative solutions :
x = -π/3
x = (π/3) - 2π = -5π/3
x = (-π/3) - 2π = -7π/3

cos(x) = 1/2 when x = pi/3 + 2pi * k and when x = -pi/3 + 2pi * k. k is an integer

Solutions from -6pi to 6pi

pi/3 - 18pi/3 , -pi/3 - 15pi/3 , pi/3 - 15pi/3 , -pi/3 - 12pi/3 , pi/3 - 12pi/3 , -pi/3 - 9pi/3 , pi/3 - 9pi/3 , -pi/3 - 6pi/3 , pi/3 - 6pi/3 , -pi/3 - 3pi/3 , pi/3 - 3pi/3 , -pi/3 , pi/3 , -pi/3 + 3pi/3 , pi/3 + 3pi/3 , -pi/3 + 6pi/3 , pi/3 + 6pi/3 , -pi/3 + 9pi/3 , pi/3 + 9pi/3 , -pi/3 + 12pi/3 , pi/3 + 12pi/3 , -pi/3 + 15pi/3 , pi/3 + 15pi/3 , -pi/3 + 18pi/3

-17pi/3 , -16pi/3, -14pi/3 , -13pi/3 , -11pi/3 , -10pi/3 , -8pi/3 , -7pi/3 , -5pi/3 , -4pi/3 , -2pi/3 , -pi/3 , pi/3 , 2pi/3 , 4pi/3, 5pi/3 , 7pi/3 , 8pi/3 , 10pi/3 , 11pi/3 , 13pi/3 , 14pi/3, 16pi/3 , 17pi/3

-4pi/3, -2pi/3, -pi/3 , pi/3 , 2pi/3 , 4pi/3

There you go.